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Source: http://video.msnbc.msn.com/nightly-news/48074044/

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Statement from CMS: Observation of a new particle with a mass of 125 GeV

ScienceDaily (July 4, 2012) ? In a joint seminar today (July 4, 2012) at CERN and the "ICHEP 2012" conference in Melbourne, researchers with the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) presented their preliminary results on the search for the standard model (SM) Higgs boson in their data recorded up to June 2012.

CMS observes an excess of events at a mass of approximately 125 GeV with a statistical significance of five standard deviations (5 sigma) above background expectations. The probability of the background alone fluctuating up by this amount or more is about one in three million. The evidence is strongest in the two final states with the best mass resolution: first the two-photon final state and second the final state with two pairs of charged leptons (electrons or muons). The interpret this to be due to the production of a previously unobserved particle with a mass of around 125 GeV.

The CMS data also rule out the existence of the SM Higgs boson in the ranges 110-122.5 GeV and 127-600 GeV with 95% confidence level -- lower masses were already excluded by CERN's LEP collider at the same confidence level.

Within the statistical and systematic uncertainties, results obtained in the various search channels are consistent with the expectations for the SM Higgs boson. However, more data are needed to establish whether this new particle has all the properties of the SM Higgs boson or whether some do not match, implying new physics beyond the standard model.

The LHC continues to deliver new data at an impressive rate. By the end of 2012, CMS hopes to have more than triple its total current data sample. These data will enable CMS to elucidate further the nature of this newly observed particle. They will also allow CMS to extend the reach of their many other searches for new physics.

CMS Search Strategy

CMS analysed the full data sample of proton-proton collisions collected in all of 2011 and in 2012, up until June 18. These data amount to up to 5.1 fb^?1 of integrated luminosity, at a centre-of-mass energy of 7 TeV in 2011 and up to 5.3 fb^?1 at 8 TeV in 2012.

The standard model predicts that the Higgs boson lasts for only a very short time before it breaks up, or "decays," into other well-known particles. CMS studied five main Higgs boson decay channels. Three channels result in pairs of bosonic particles (??, ZZ or WW) and two channels result in pairs of fermionic particles (bb or ??), where ? denotes a photon, Z and W denote the force carriers of the weak interaction, b denotes a bottom quark, and ? denotes a tau lepton. The ??, ZZ and WW channels are equally sensitive in the search for a Higgs boson around 125 GeV and all are more sensitive than the bb and ?? channels.

The ?? and ZZ channels are especially important as they both allow the mass of the new particle to be measured with precision. In the ?? channel the mass is determined from the energies and directions of two high-energy photons measured by the CMS crystal electromagnetic calorimeter (ECAL). In the ZZ channel the mass is determined from the decays of the two Zs to two pairs of electrons, or two pairs of muons, or a pair of electrons and a pair of muons. These are measured in the ECAL, inner tracking and muon detectors.

The WW channel is more complex. Each W is identified through its decay to an electron and a neutrino or a muon and a neutrino. The neutrinos pass through the CMS detectors undetected, so the SM Higgs boson in the WW channel would manifest itself as a broad excess in the mass distribution, rather than a narrow peak. The bb channel has large backgrounds from standard model processes, so the analysis searches for events in which a Higgs boson is produced in association with a W or Z, which then decays to electron(s) or muon(s). The ?? channel is measured by observing ? decays to electrons, muons and hadrons.

CMS Search Results

The CMS data sample should be sensitive enough to completely exclude the mass range 110-600 GeV at 95% confidence level, if the SM Higgs does not exist. In fact, the CMS data do rule out the existence of the SM Higgs boson in two broad mass ranges of 110-122.5 GeV and 127-600 GeV with 95% confidence level.

The range of 122.5-127 GeV cannot be excluded because the scientists see an excess of events in three of the five channels analysed:

• ?? channel: the ?? mass distribution. There is an excess of events above background with a significance of 4.1 sigma, at a mass near 125 GeV. The observation of the two-photon final state implies that the new particle is a boson, not a fermion, and that it cannot be a "spin 1" particle.
• ZZ channel: the mass distribution for the four leptons (two pairs of electrons, or two pairs of muons, or the pair of electrons and the pair of muons). Accounting also for the decay angle characteristics, it yields an excess of 3.2 sigma above background at a mass near 125 GeV.
• WW channel: a broad excess in the mass distribution of 1.5 sigma is observed.
• bb and ?? channels: no excess is observed.

The statistical significance of the signal, from a combined fit to all five channels, is 4.9 sigma above background. A combined fit to just the two most sensitive and high-resolution channels (?? and ZZ) yields a statistical significance of 5.0 sigma. The probability of the background alone fluctuating up by this amount or more is about one in three million.

The mass of the new particle is determined to be 125.3 ? 0.6 GeV, independent of any assumptions about the expected relative yields of the decay channels. The measured production rate (?_DAT) of this new particle is consistent with the predicted rate (?_SM) for the SM Higgs boson: ?_DAT/?_SM = 0.80 ? 0.22.

Great care has also been taken to understand numerous details of the detector performance, the event selection, background determinations and other possible sources of systematic and statistical uncertainties. The 2011 analysis showed an excess of events at about 125 GeV. Therefore, to avoid a potential bias in the choice of selection criteria for the 2012 data that might artificially enhance this excess, the 2012 data analysis was performed "blind," meaning that the region of interest was not examined until after all the analysis criteria had been fully scrutinized and approved.

As a general cross-check, the analyses were performed by at least two independent teams. A number of other features reinforce confidence in the results:

• The excess is seen at around 125 GeV in both the 2011 data sample (7 TeV) and the 2012 data sample (8 TeV);
• The excess is seen at the same mass in both the high-resolution channels (?? and ZZ);
• The excess seen in the WW is consistent with one that would arise from a particle at 125 GeV;
• The excess is seen in a range of final states involving photons, electrons, muons and hadrons.

The preliminary results presented today will be refined, with the aim of submitting them for publication towards the end of the summer.

Future Plans

The new particle observed at about 125 GeV is compatible, within the limited statistical accuracy, with being the SM Higgs boson. However, more data are required to measure its properties such as decay rates in the various channels (??, ZZ, WW, bb and ??) and ultimately its spin and parity, and hence ascertain whether it is indeed the SM Higgs boson or the result of new physics beyond the standard model.

The LHC continues to perform extremely well. By the end of 2012, CMS expects to more than triple its total data sample, and hence to probe further the nature of this new particle. If this particle is indeed the SM Higgs boson, its properties and implications for the standard model will be studied in detail. If it is not the SM Higgs boson, CMS will explore the nature of the new physics that it implies, which may include additional particles that are observable at the LHC. In either case, searches will also continue for other new particles or forces that can be observed in future runs of the LHC at higher beam energies and intensities.

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Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/AU16avS1zyc/120704113937.htm

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Fish learn to cope in a high CO2 world

Tuesday, July 3, 2012

Some coral reef fish may be better prepared to cope with rising CO2 in the world's oceans ? thanks to their parents.

Researchers at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) today reported in the journal Nature Climate Change, encouraging new findings that some fish may be less vulnerable to high CO2 and an acidifying ocean than previously feared.

"There has been a lot of concern around the world about recent findings that baby fish are highly vulnerable to small increases in acidity, as more CO2 released by human activities dissolves into the oceans," says Dr Gabi Miller of CoECRS and James Cook University.

"Our work with anemone fish shows that their babies, at least, can adjust to the changes we expect to occur in the oceans by 2100, provided their parents are also raised in more acidic water."

"Human activity is expected to increase the acidity of the world's oceans by 0.3 to 0.4 pH by the end of this century, on our present trends in CO2 emissions," co-researcher Prof Philip Munday says.

"Previous studies, and our own research, have shown that growth and survival of juvenile fish can be seriously affected when the baby fish are exposed to these sorts of CO2 and pH levels," he says.

"However when we exposed both parents and their offspring in more acidic water we found that the anemone fish, at least, were able to compensate for the change" says Dr Miller. Whether this effect lasts all their lives, remains to be seen." she adds.

How parent fish actually pass on this ability to deal with acidity to their offspring is still a mystery, says Prof Munday. "The time interval is too short for it to be genetic adaptation in the normal sense. However, it's an important parental effect that we need to factor in as we assess the vulnerability of the world's fish stocks to the planet-wide changes in ocean chemistry that humans are now causing."

Based on evidence from past major extinction events, scientists have long feared that the acidity caused by the release of high levels of CO2 could cause havoc among sea-life, especially those which depend on calcium to form their bones and shells. New research has also shown that higher CO2 levels can cause the nervous systems of some marine species to malfunction.

The recent increase in ocean acidity due to human activity in releasing carbon ? about 0.1 of a pH unit over the last half century ? is thought to be steeper even than in any of the past major extinctions, which eliminated between 70-90 per cent of marine species.

"What this research shows is that some species, at least, may have more capacity to cope than we thought ? which could help buy time for humanity to bring its CO2 emission under control," Prof Munday says.

However Dr Miller cautions that anemone fish are particularly hardy by nature, and may not be typical of all fish in the ocean. "They are definitely not the 'canary in the coal mine', as they have quite a large ability to cope with changed conditions anyway," she says. "We need to extend these studies to other types of fish, especially those which humans rely on for food."

Both scientists warn that the major impact on ocean acidification is likely to be on the corals themselves, and the reefs which they form, which in turn provide the habitat for small fish such as the anemone fish. The fate of the world's reefs under a high human CO2 regime remains highly uncertain, they caution.

Their paper 'Parental environment mediates impacts of elevated CO2 on a coral reef fish' by Gabrielle M. Miller, Sue-Ann Watson, Jennifer M. Donelson, Mark I. McCormick and Philip L. Munday appears in the online issue of the journal Nature Climate Change.

The team will present a paper on their work to the 12th International Coral Reef Symposium, Cairns, Australia on July 13, 2012.

###

ARC Centre of Excellence in Coral Reef Studies: http://www.coralcoe.org.au/

Thanks to ARC Centre of Excellence in Coral Reef Studies for this article.

This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.

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Source: http://www.labspaces.net/121445/Fish_learn_to_cope_in_a_high_CO__world

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Saints' coach Payton, wife file divorce petitions

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Source: http://news.yahoo.com/saints-coach-payton-wife-file-divorce-petitions-172112852--nfl.html

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Puerto Rico sees sharp spike in dengue cases

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Source: http://news.yahoo.com/puerto-rico-sees-sharp-spike-dengue-cases-173542821.html

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Higher energies for laser-accelerated particles possible

Public release date: 2-Jul-2012
[ | E-mail | Share ]

Contact: Anja Weigl
a.weigl@hzdr.de
49-351-260-2452
Helmholtz Association of German Research Centres

The use of compact laser accelerators for cancer therapy with charged particles such as protons could become possible in the future if scientists succeed in generating protons with very high energies. Physicists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) directed the light of the high power laser DRACO perpendicularly and obliquely onto a thin metal foil; thus, permitting them to demonstrate for the first time that accelerated protons follow the direction of the laser light. By incorporating this new data into a conventional model describing the laser particle acceleration, high proton energies which have not been realized so far might become achievable. The results have been published in the scientific journal Nature Communications.

The intense and ultra-short light pulses of the high power laser DRACO can be thought of as disks of about 10 centimeters in diameter and being as thin as a normal sheet of paper. If one of these disks of light is focused onto a thin metal foil, the extreme high electric and magnetic forces will pull negatively charged electrons out of the foil. These electrons will then accelerate positively charged protons away from the foil's surface. To date, many experts have thought that commercially available laser systems would not be suitable for future cancer therapy applications because they have such short laser pulses, and the energy which is achieved by the accelerated protons is correspondingly too low. The results published by the HZDR group demonstrate for the first time that proton energies needed for cancer therapy could, in principle, also be generated from such a short pulse laser. This prospect motivated the Dresden researchers to study the particle acceleration process very closely.

New Two-Phase Model for Laser Accelerated Particles

A light pulse coming from the DRACO laser and directed perpendicular onto a thin metal foil accelerates electrons, and thus also protons, perpendicularly to the foil's surface, just like previous models predict. But that is not the case with a tilted laser pulse. If the angle of the thin light disk is slightly tilted with respect to the axis of propagation, something unexpected happens during the first phase of the particle acceleration. The electrons feel the rotation of the light disk and follow the direction in which the light hits the foil. Moreover, protons are accelerated along this direction as well and, in contrast to the electrons, maintain their direction. This novel observation of the directional dependence permits the Dresden physicists to also look directly at the underlying acceleration process.

"During the first acceleration phase, the distance between the electrons and the foil is extremely small. Once the short laser pulse has pushed them through the foil, they immediately swing back again because the foil has a positive charge. That is one reason why we were very surprised to discover that not only the electrons follow the motion of the laser light, but also the protons exhibit this previously unknown directional dependence," notes the doctoral candidate and main author of the current publication, Karl Zeil. He managed to detect another particular feature which only occurs with ultra-short laser pulses: The initial phase is decisive for the entire acceleration process. During the first 30 femtoseconds that is, one millionth of one billionth of a second, and equal to the length of the laser pulse the acceleration is very efficient. The short and efficient acceleration phase is followed by a longer expansion phase, during which a uniform and symmetrical plasma cloud is formed. The protons, however, gain so much energy during the first phase which, in turn, makes them so fast that they finally can reach higher energies than conventional models would predict.

Precisely how the fast electrons oscillate around the foil, and thus, accelerate the protons, is investigated by the HZDR scientists also with the help of simulations. Karl Zeil: "Experiments and simulations agree quite well with each other. With the newly obtained data we can now extend the presently existing models. This essentially means that ultra-short pulsed lasers like our DRACO laser could potentially be capable of generating protons with sufficiently high energy so that they can be used in future cancer therapy. That we were successful in obtaining these results is both very pleasing and very motivating."

DRACO Being Expanded, PENELOPE Newly Added

The DRACO laser currently reaches a peak power of 150 terawatts this translates into the output of all power plants in the world albeit only for a period of 30 femtoseconds at a time. The laser physicists at the Helmholtz-Zentrum Dresden-Rossendorf want to expand DRACO to 500 terawatts and are currently building a petawatt laser system called PENELOPE. As a modern accelerator technology, particle acceleration with laser light provides considerable advantages when compared to conventional systems: The acceleration distance is much shorter and the costs for such systems are potentially lower. Currently, the OncoRay center, which is jointly supported by the cooperation partners HZDR, University Hospital, and TU Dresden, is building a modern proton therapy facility on the University Hospital's campus. The new facility will be used for cancer research and therapy. For the first time ever, the prototype of a high performance laser will be operated here in addition to a conventional proton accelerator.

###

Publication
K. Zeil u.a., "Direct observation of prompt pre-thermal laser ion sheath acceleration, in: Nature Communications, Volume 3 (2012), Article number 874, DOI: 10.1038/ncomms1883.

Further information
Prof. Ulrich Schramm | Karl Zeil
Institute of Radiation Physics
Phone +49 351 260-2471 | -2614
u.schramm@hzdr.de | k.zeil@hzdr.de

Media contact
Anja Weigl
Phone +49 351 260-2452
a.weigl@hzdr.de | www.hzdr.de

Helmholtz-Zentrum Dresden-Rossendorf | Bautzner Landstr. 400 | 01328 Dresden | Germany

The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) conducts research in the sectors matter, health, and energy. The HZDR research focuses on the following topics:

• How does matter behave in strong fields and at small-scale dimensions?
• How can malignant tumors be identified at an early stage and treated effectively?
• How can resources and energy be used safely and efficiently?

To answer these scientific questions, five large-scale research facilities provide, in part, unique research opportunities. These facilities are also accessible to external users.

The HZDR has been a member of the Helmholtz Association, Germany's largest research organization, since January 1, 2011. It has four locations in Dresden, Leipzig, Freiberg, and Grenoble and employs about 900 people approx. 400 of whom are scientists including 140 doctoral candidates.

---

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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Public release date: 2-Jul-2012
[ | E-mail | Share ]

Contact: Anja Weigl
a.weigl@hzdr.de
49-351-260-2452
Helmholtz Association of German Research Centres

The use of compact laser accelerators for cancer therapy with charged particles such as protons could become possible in the future if scientists succeed in generating protons with very high energies. Physicists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) directed the light of the high power laser DRACO perpendicularly and obliquely onto a thin metal foil; thus, permitting them to demonstrate for the first time that accelerated protons follow the direction of the laser light. By incorporating this new data into a conventional model describing the laser particle acceleration, high proton energies which have not been realized so far might become achievable. The results have been published in the scientific journal Nature Communications.

The intense and ultra-short light pulses of the high power laser DRACO can be thought of as disks of about 10 centimeters in diameter and being as thin as a normal sheet of paper. If one of these disks of light is focused onto a thin metal foil, the extreme high electric and magnetic forces will pull negatively charged electrons out of the foil. These electrons will then accelerate positively charged protons away from the foil's surface. To date, many experts have thought that commercially available laser systems would not be suitable for future cancer therapy applications because they have such short laser pulses, and the energy which is achieved by the accelerated protons is correspondingly too low. The results published by the HZDR group demonstrate for the first time that proton energies needed for cancer therapy could, in principle, also be generated from such a short pulse laser. This prospect motivated the Dresden researchers to study the particle acceleration process very closely.

New Two-Phase Model for Laser Accelerated Particles

A light pulse coming from the DRACO laser and directed perpendicular onto a thin metal foil accelerates electrons, and thus also protons, perpendicularly to the foil's surface, just like previous models predict. But that is not the case with a tilted laser pulse. If the angle of the thin light disk is slightly tilted with respect to the axis of propagation, something unexpected happens during the first phase of the particle acceleration. The electrons feel the rotation of the light disk and follow the direction in which the light hits the foil. Moreover, protons are accelerated along this direction as well and, in contrast to the electrons, maintain their direction. This novel observation of the directional dependence permits the Dresden physicists to also look directly at the underlying acceleration process.

"During the first acceleration phase, the distance between the electrons and the foil is extremely small. Once the short laser pulse has pushed them through the foil, they immediately swing back again because the foil has a positive charge. That is one reason why we were very surprised to discover that not only the electrons follow the motion of the laser light, but also the protons exhibit this previously unknown directional dependence," notes the doctoral candidate and main author of the current publication, Karl Zeil. He managed to detect another particular feature which only occurs with ultra-short laser pulses: The initial phase is decisive for the entire acceleration process. During the first 30 femtoseconds that is, one millionth of one billionth of a second, and equal to the length of the laser pulse the acceleration is very efficient. The short and efficient acceleration phase is followed by a longer expansion phase, during which a uniform and symmetrical plasma cloud is formed. The protons, however, gain so much energy during the first phase which, in turn, makes them so fast that they finally can reach higher energies than conventional models would predict.

Precisely how the fast electrons oscillate around the foil, and thus, accelerate the protons, is investigated by the HZDR scientists also with the help of simulations. Karl Zeil: "Experiments and simulations agree quite well with each other. With the newly obtained data we can now extend the presently existing models. This essentially means that ultra-short pulsed lasers like our DRACO laser could potentially be capable of generating protons with sufficiently high energy so that they can be used in future cancer therapy. That we were successful in obtaining these results is both very pleasing and very motivating."

DRACO Being Expanded, PENELOPE Newly Added

The DRACO laser currently reaches a peak power of 150 terawatts this translates into the output of all power plants in the world albeit only for a period of 30 femtoseconds at a time. The laser physicists at the Helmholtz-Zentrum Dresden-Rossendorf want to expand DRACO to 500 terawatts and are currently building a petawatt laser system called PENELOPE. As a modern accelerator technology, particle acceleration with laser light provides considerable advantages when compared to conventional systems: The acceleration distance is much shorter and the costs for such systems are potentially lower. Currently, the OncoRay center, which is jointly supported by the cooperation partners HZDR, University Hospital, and TU Dresden, is building a modern proton therapy facility on the University Hospital's campus. The new facility will be used for cancer research and therapy. For the first time ever, the prototype of a high performance laser will be operated here in addition to a conventional proton accelerator.

###

Publication
K. Zeil u.a., "Direct observation of prompt pre-thermal laser ion sheath acceleration, in: Nature Communications, Volume 3 (2012), Article number 874, DOI: 10.1038/ncomms1883.

Further information
Prof. Ulrich Schramm | Karl Zeil
Institute of Radiation Physics
Phone +49 351 260-2471 | -2614
u.schramm@hzdr.de | k.zeil@hzdr.de

Media contact
Anja Weigl
Phone +49 351 260-2452
a.weigl@hzdr.de | www.hzdr.de

Helmholtz-Zentrum Dresden-Rossendorf | Bautzner Landstr. 400 | 01328 Dresden | Germany

The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) conducts research in the sectors matter, health, and energy. The HZDR research focuses on the following topics:

• How does matter behave in strong fields and at small-scale dimensions?
• How can malignant tumors be identified at an early stage and treated effectively?
• How can resources and energy be used safely and efficiently?

To answer these scientific questions, five large-scale research facilities provide, in part, unique research opportunities. These facilities are also accessible to external users.

The HZDR has been a member of the Helmholtz Association, Germany's largest research organization, since January 1, 2011. It has four locations in Dresden, Leipzig, Freiberg, and Grenoble and employs about 900 people approx. 400 of whom are scientists including 140 doctoral candidates.

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Source: http://www.eurekalert.org/pub_releases/2012-07/haog-hef070212.php

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